Reacción a "European Southern Observatory denounces industrial megaproject threatening Chile's Paranal Observatory, the world's darkest observatory"

The recently published study on light pollution in Chile, prepared by some of the world's leading experts in modelling, offers in principle the highest scientific guarantees. The data it presents confirms a growing concern: in Chile, light pollution has increased significantly in the last decade. We documented this in the study we organised at the Complutense University of Madrid and this trend continues to consolidate.

One of the main problems of Chilean legislation, at least in its best known version, is that it does not adequately consider the cumulative impact of different installations in an area, which introduces a risk factor for the preservation of dark skies. This is especially relevant in large-scale projects such as this one, which are located close to virtually pristine areas. These areas, so far, have minimal levels of light pollution, mainly limited to the skyline.

However, the construction of a mega-project as close as 5 to 10 kilometres away could have significant impacts. Not only would it increase direct light pollution through light emission, but it would also contribute to an increase of dust in the atmosphere, aggravating light scattering and affecting the quality of the night sky. This represents a considerable risk to the preservation of one of Chile's most valuable natural resources: its dark skies, which are a world reference for astronomy and science.

It is essential that any project of this nature rigorously considers both direct and cumulative impacts on the environment. Chile's dark skies are not only scientific, but also cultural and natural heritage, and their preservation should be an international priority.

The Cerro Paranal telescopes are the southern hemisphere's main window on the universe, and the new very large telescope, the ELT, is being built nearby on Cerro Armazones. To affect the quality of astronomical observation in these areas is to significantly damage the long-term ability of human beings to do science. You have to think that if light is constantly running it is a very bad precedent. The light itself would affect and increase the cost of operating the observatory, but I don't think it's as bad as the amount of dust it can disperse. Dust amplifies the light pollution not only from this site but from any other surrounding site.